A modern passenger aircraft commonly includes a ventilation system that is configured to direct a stream of cooled (or heated) air towards each passenger onboard the aircraft. Typically, each passenger is presented with an adjustable nozzle that is mounted in an overhead compartment and which the passenger can manipulate and reposition to control the direction of the stream of air. For example, the nozzle may be configured as a sphere and may be mounted in a ball socket in the overhead compartment. By moving the spherical nozzle in the ball socket, the passenger can control the direction of the stream of air.
The nozzle also includes an integrated valve that the passenger may open and/or close at will. Commonly, the valve is a pintle valve that includes a pintle and an opening that is configured to engage with, and to be obstructed by, the pintle. As the passenger unscrews and/or screws an actuator on the nozzle, the pintle is retracted and/or extended causing the pintle valve to open and/or close, respectively. When the pintle valve is opened, the stream of air flows out of the nozzle and when the pintle valve is closed, the stream of air is cut off. Accordingly, the conventional ventilation system described above allows each passenger to turn the stream of air on and off at will and to direct the stream of air towards a desired target. This level of control provides for the comfort of the passengers. This style of adjustable ventilation is commonly referred to as a ‘gasper’ in aviation applications.
Another feature of the above described ventilation system that aircraft passengers have found satisfying is the relatively high velocity of the stream of air that is produced by such a ventilation systems. The production of a relatively high velocity stream of air has proven to be very effective at cooling/warming passengers in the aircraft's cabin. The high velocity of the stream of air is typically achieved as a result of the nozzle's configuration. In a conventional nozzle, an upstream portion of the nozzle has a larger diameter than a downstream portion of the nozzle. Accordingly, as a relatively low speed flow of air enters the nozzle, the area of the passageway through which the flow of air passes begins to constrict. This constriction tightens as the flow of air continues down stream through the nozzle. This constriction causes the flow of air to accelerate as the flow of air moves through the nozzle in order to maintain a constant mass-flow rate.
While the above described ventilation system is adequate, there is room for improvement. The movement and the acceleration of the flow of air through the nozzle causes the emission of an appreciable hissing sound as the stream of air exits the nozzle. In many applications, the hissing sound made by the ventilation system is not appreciably louder than the background noise in the cabin of an aircraft and is therefore acceptable. However, some aircraft (e.g., privately owned corporate jets) are designed, constructed, and/or configured to provide a reduced level of background noise within the cabin during aircraft operations as compared with conventional commercial aircraft. In such aircraft, the noise generated by the ventilation system may be quite noticeable and/or unacceptable to potential customers.
Previous attempts to quiet the ventilation system have included the use of different types of valves in the nozzle. Other attempts have included reducing the air pressure of the air flowing past the valve which, in turn, yields a lower speed stream of air. These solutions have not been effective. For example, while the use of different types of valves in the nozzle has, to some extent, yielded reduced decibel readings at the nozzle's exit, such volume reductions have been insufficient. Additionally, while the reduction of the air pressure of the air flowing through the nozzle has proven effective at reducing the decibel level of the noise produced by the stream of air exiting the nozzle, such reduction of air pressure greatly reduced the speed of the stream of air exiting the nozzle. Such a reduction in the speed of the stream of air exiting the nozzle has resulted in an unacceptable diminution in the effectiveness of the ability of the stream of air to cool/warm aircraft passengers.
Accordingly, it is desirable to provide a ventilation system that produces a relatively quiet, high speed stream of air. In addition, it is desirable to provide a method for assembling such a ventilation system. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.